As Jai has pointed out, we can't get in to view these courses, however there are some things you can do to start identifying the cause of / solving the problem.
The images aren't likely to be a problem. I presume that the times you mentioned are from the performance info in the footer, and page "weight" isn't considered in this stat - just the actual time to generate the page on the server
1. Make sure you're running newish Moodle. Moodle 1.9 has all sorts of performance optimisations that make it tons faster (not to mention more robust, secure, and of course feature-rich).
2. A quick search of this forum will show you that a likely cause of the slowness is a dodgy block. The best strategy in these cases is to compare the two courses to see which blocks differ... and to try disabling blocks to isolate the cause.
3. What else is different? There are other things (most notably Groups) that can affect the performance... what else can you tell us about what's going on? Are you logging in as the same user? Do page load times vary significantly for different types of user (ie. for students vs teachers/admins?)
Hope this gets you a little further down the path to solving your hassles,